<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* .wrap {
      width: 500px;
      height: 500px;
      background-color: red;
      margin-top: 100px;
      overflow: hidden;
    }

    .box {
      width: 100px;
      height: 100px;
      background-color: blue;
      margin-top: 200px;
    } */

    /* .wrap {
      width: 500px;
      background-color: red;
      overflow: hidden;
    }

    .box1 {
      width: 100px;
      height: 100px;
      background-color: blue;
      float: left;
    }

    .box2 {
      width: 100px;
      height: 100px;
      background-color: green;
      float: left;
    } */

    .wrap {
      width: 500px;
      height: 500px;
      background-color: red;
    }

    .con {
      overflow: hidden;
    }

    .box1 {
      width: 100px;
      height: 100px;
      background-color: blue;
      margin-bottom: 100px;
    }

    .box2 {
      width: 100px;
      height: 100px;
      background-color: green;
      margin-top: 100px;
    }

    .trapzoid{
       border-bottom: 100px solid red;
       border-left: 50px solid transparent;
       border-right: 50px solid transparent;
       width: 100px;
   }
   .san{
       width:0;
       height:0;
       border-left:50px solid transparent;
       border-right:50px solid transparent;
       border-bottom:100px solid red;
   }
  </style>
</head>
<body>
  <div class="trapzoid"></div>
  <div class="san"></div>
</body>
</html>
 